The conventional inverse phase converter has a magnetic core located in a bobbin. The bobbin is wound with coils of the same or different diameters to become a first side coil and a second side coil. The magnetic core wound with the first side coil and the second side coil is encased in shell to become an induction coil inverse phase converter. The present liquid crystal display (LCD) has a back light module which generates light through CCFLs that are compact and powerful. The CCFLs are driven by high voltage electric power. Hence the CCFLs require the inverse phase converter to generate light to serve as the light source of the LCD.
As large display device has gradually become the mainstream of the market, a plurality of CCFLs are needed to provide light and achieve a desirable display effect. As a result, the demand of supporting multiple CCFLs through a single inverse phase converter increases. R.O.C. patent No. M267607 discloses an inverse phase converter that has multiple coils winding on a primary side winding zone to generate more magnetic sheaves so that high voltage may be generated on a secondary side winding zone to supply electricity required by one or more CCFLs. Its coils are wound on a hollow bobbin with two spacers dividing the bobbin into three zones. The three zones include a pair of secondary side winding zones on two sides and a primary side winding zone in the middle.
In order to generate the high voltage, the winding number of coils on the primary side winding zone must be increased. But the two sides of the primary side winding zone are occupied by the second side winding zones. Hence the winding coil can only be stacked upwards. This creates difficulty of installation on the circuit board. Moreover, the inverse phase converter could be easily overheated. To reduce the heat generated by the winding coil, the diameter of the bobbin on the primary side winding zone must be larger. As the winding space of the primary side winding zone is restricted, the number of coils that can be wound decreases. This affects the voltage output of the inverse phase converter. As a result, the number of installable CCFLs also is limited.
Moreover, to increase the number of the winding coil by increasing the length of the primary side winding zone requires a longer magnetic core. This creates quality problem of magnetic core fabrication. The performance of the inverse phase converter also is impacted.